Rob Valdivia, Senior VFX Artist at Sledgehammer Games, has updated his Linkedin profile with the following info:

MW4 Rumor: Sledgehammer Games working on Modern Warfare 4?

Rob hints that Sledgehammer is indeed working on a new Modern Warfare. We could think this info could be related with MW3, but his portfolio was updated in April 2013. Therefore, we are speaking upon a new game in the series.

We are going to suppose that Activision is preparing this new MW, we will have one Call of Duty from Infinity Ward, other from Treyarch and another one from Sledgehammer Games. Activision could release one CoD per year, but one would have three years of development or Activision could release two games in one year. I think it’s better to look forward until an official confirmation from Activision. Price is back folks?